초고압 처리에 의한 메밀 반죽의 변화를 반죽의 미세 구조, 열 특성 평가, 조직감 측정을 통하여 확인하였다. 초고압 처리 강도와 시간에 따라 메밀 반죽 내 미세 구조를 관찰 시, 압력의 강도와 처리 시간이 증가함에 따라 전분의 호화가 일어나며 조밀한 구조를 가지게 되었다. 이러한 현상은 메밀 반죽의 조직감에 영향을 미쳐 압력이 증가함에 따라 탄성, 부착성, 씹힘성을 감소시키고 압력 처리 시간을 달리하였을 때 장시간 압력 처리에 따라 탄성, 씹힘성, 검성이 더 높은 값을 가짐을 확인하였다. 면의 끊어짐에 관련된 특성인 인장도는 소비자가 면을 섭취할 때 관능적 품질의 중요한 요소로서, 초고압 처리 시 글루텐을 함유하지 않는 메밀 반죽의 인장성을 나타내는 failure tensile distance를 증가시키는 결과를 얻었다. 따라서 메밀을 비롯한 다른 곡물을 활용한 gluten-free면 제품의 제조 시 초고압공정을 활용할 경우 기존 제품의 단점을 개선할 수 있을 것으로 예상된다.

The effect of adding Ca on the microstructural and mechanical properties of as-cast Mg-11Li-3Zn-1Sn(wt%) alloys were investigated. Mg-11Li-3Zn-1Sn-0.4Mn with different Ca additions (0.4, 0.8, 1.2 wt%) were cast under an SF6 and Co2 atmosphere at 720 oC. The cast billets were homogenized at 400 oC for 12h and extruded at 200 oC. The microstructural and mechanical properties were analyzed by OM, XRD, SEM, and tensile tests. The addition of Ca to the Mg-11Li-3Zn-1Sn-0.4Mn alloy resulted in the formation of Ca2Mg6Zn3, MgSnCa intermetallic compound. By increasing Ca addition, the volume fraction and size of Ca2Mg6Zn3 with needle shape were increased. This Ca2Mg6Zn3 intermetallic compound was elongated to the extrusion direction and refined to fine particles due to severe deformation during hot extrusion. The elongation of the 0.8 wt% Ca containing alloy improved remarkably without reduction strength due to the formation of fine grain and Ca2Mg6Zn3 intermetallic compounds by Ca addition. It is probable that fine and homogeneous Ca2Mg6Zn3 intermetallic compounds played a significant role in the increase of mechanical properties.

This study investigated the microstructure and wear resistance property of HPHT (high pressure high temperature) sintered PDC (polycrystalline diamond compact) in accordance with initial molding pressure. After quantifying an identical amount of diamond powder, the powder was inserted in top of WC-Co sintered material, and molded under four different pressure conditions (50, 100, 150, 200 kgf/cm2). The obtained diamond compact underwent sintering in high pressure, high temperature conditions. In the case of the 50 kgf/cm2 initial molding pressure condition, cracks were formed on the surface of PDC. On the other hand, PDCs obtained from 100~200 kgf/cm2 initial molding pressure conditions showed a meticulous structure. As molding pressure increased, low Co composition within PDC was detected. A wear resistance test was performed on the PDC, and the 200 kgf/cm2 condition PDC showed the highest wear resistance property.

In this study, the effect of the friction stir welding (FSW) was compared with that of the gas tungsten arc welding (GTAW) on the microstructure and microhardness of Cu-Ni alloy weldment. The weldment of 10 mm thickness was fabricated by FSW and GTAW, respectively. Both weldments were compared with each other by optical microstructure, microhardness test and grain size measurement. Results of this study suggest that the microhardness decreased from the base metal (BM) to the heat affected zone (HAZ) and increased at fusion zone (FZ) of GTAW and stir zone (SZ) of FSW. the minimum Hv value of both weldment was obtained at HAZ, respectively, which represents the softening zone, whereas Hv value of FSW weldment was little higher than that of GTAW weldment. These phenomena can be explained by the grain size difference between HAZs of each weldment. Grain size was increased at the HAZ during FSW and GTAW. Because FSW is a solid-state joining process obtaining the lower heat-input generated by rotating shoulder than heat generated in the arc of GTAW.

This study investigates the microstructure and thermal shock properties of polycrystalline diamond compact (PDC) produced by the high-temperature, high-pressure (HPHT) process. The diamond used for the investigation features a 12~22 μm- and 8~16 μm-sized main particles, and 1~2 μm-sized filler particles. The filler particle ratio is adjusted up to 5~31% to produce a mixed particle, and then the tap density is measured. The measurement finds that as the filler particle ratio increases, the tap density value continuously increases, but at 23% or greater, it reduces by a small margin. The mixed particle described above undergoes an HPHT sintering process. Observation of PDC microstructures reveals that the filler particle ratio with high tap density value increases direct bonding among diamond particles, Co distribution becomes even, and the Co and W fraction also decreases. The produced PDC undergoes thermal shock tests with two temperature conditions of 820 and 830, and the results reveals that PDC with smaller filler particle ratio and low tap density value easily produces cracks, while PDC with high tap density value that contributes in increased direct bonding along with the higher diamond content results in improved thermal shock properties.

기술의 급속한 발전, 글로벌화된 시장 및 사회환경은 기업들에게 전통적 관료제에서 강조해 온 효율성 뿐만 아니라 혁신과 품질에 대한 경쟁압력을 가하고 있다. 이에 따라 관료제를 넘어서 참여, 평등, 협동의 원리가 강조되는 공동체주의적(communitarian) 기업모델이 등장하면서 인사관리 또한 통제중심에서 몰 입지향 인사관리(commitment oriented HRM)로의 전환이 이루어지고 있다. 본 연구는 공동체주의적 기 업의 구조적 특성 파악의 일환으로 한국노동연구원의 사업장패널조사(WPS2011) 자료를 토대로 하여 우 리나라의 인사관리 및 노사관계에서 사업장내 인사이슈에 대한 근로자참여(즉, 몰입지향 인사관리)와 조 직의사소통 (참여)의 관계와 이들 활동이 혁신에 어떻게 영향 미치는지 분석하였다. 검정결과, 첫째 몰입 지향 인사관리특성을 갖춘 사업장일수록 혁신활동 및 성과가 높은 것으로 나타났다. 둘째, 상향, 하향 및 수평(노사) 조직의사소통이 모두 활발히 이루어지는 사업장일수록 혁신활동 및 성과가 우수한 것으로 나 타났다. 마지막으로 몰입지향 인사관리와 혁신활동 및 성과의 관계는 상향, 하향 및 수평(노사) 조직의사 소통 모두에 의해 완전매개되는 것으로 판정되었다. 이는 몰입지향 인사관리(또는 참여적 노사관계)의 주요 목적이자 가치인 사회적 효용(social utility)을 달성하기 위해서 상향 및 하향의 조직의사소통 방향 뿐만 아니라 사용자와 근로자간 (수평) 의사소통의 질이 모두 개선될 필요가 있다는 점을 시사한다. 사회, 기업 및 사업장 차원(단위)에서 몰입지향 인사관리(또는 참여적 노사관계)가 토착화되기 위하여 향후연 구에서는 인사 및 노사이슈에 대한 인사부서와 근로자대표기구 및 근로자의 (모범적인) 역할관계의 정립 과 그에 관한 다양한 실증분석이 지속적으로 이루어질 필요가 있을 것으로 보인다.

We evaluated the developed microstructures and mechanical properties of a severely plastically deformed Ni-30Cr alloy. Normal rolling and differential speed rolling were used as deformation processes, and the thicknesses of the specimens were reduced to 68 % of the original thickness after holding at 700 oC for 10 min and annealing at 700 oC for 40 min to obtain a fully recrystallized microstructure. Electron backscattering diffraction was used to analyze the characteristic distribution of the grain boundaries on the deformed and annealed specimens. Differential speed rolling was more effective for refining grains in comparison with normal rolling. The grain size was refined from 33 mm in the initial material to 8.1 mm with normal rolling and 5.5 mm with differential speed rolling. The more refined grain in the differential-speed-rolled material directly resulted in increases in the yield and tensile strengths by 68 % and 9.0%, respectively, compared to normal rolling. We systematically explain the relationship between the grain refinement and mechanical properties through a plastically deformed Ni-30Cr alloy based on the development of a deformation texture. The results of our study show that the DSR process is very effective when used to enhance the mechanical properties of a material through grain refinement.

As well-known wrought stainless steel, sintered stainless steel (STS) has excellent high-temperature anticorrosion even at high temperature of 800ºC, and exhibits good corrosion resistance in air. However, when temperature increases above 900ºC, the corrosion resistance of STS begins to deteriorate and dramatically decreases. In this study, the effects of phase and composition of STS on high-temperature corrosion resistances are investigated for STS 316L, STS 304 and STS 434L above 800ºC. The morphology of the oxide layers are observed. The oxides phase and composition are identified using X-ray diffractometer and energy dispersive spectroscopy. The results demonstrate that the best corrosion resistance of STS could be improved to that of 434L. The poor corrosion resistance of the austenitic stainless steels is due to the fact that NiFe2O4 oxides forming poor adhesion between the matrix and oxide film increase the oxidation susceptibility of the material at high temperature.

In this study, the control of microstructure for increasing surface roughness of Al with an electro-chemical reaction and a post treatment is systematically investigated. The Al specimen is electro-chemically treated in an electrolyte. In condition of the post treatment at 100oC for 10 min, a change of the surface microstructure occur at 50V (5 min), and a oxidized layer is at 400V, to which lead a decreasing surface roughness. The minimum temperature of the post treatment for a change of microstructure is 80oC. Moreover, in the condition of 300V (5 min), the electro-chemical reaction is followed by the post treatment at 100oC, the critical enduring time for the change of microstructure is 3 min. The longer post treatment time leads to the rougher surface. The treated Al specimen demonstrate better heat release ability owing to the higher surface roughness than the non-treated Al.

The present study deals with the effects of tempering treatment on the microstructure and mechanical properties of Cu-bearing high-strength steels. Three kinds of steel specimens with different levels of Cu content were fabricated by controlled rolling and accelerated cooling, ; some of these steel specimen were tempered at temperatures ranging from 350˚C to 650˚C for 30 min. Hardness, tensile, and Charpy impact tests were conducted in order to investigate the relationship of microstructure and mechanical properties. The hardness of the Cu-added specimens is much higher than that of Cu-free specimen, presumably due to the enhanced solid solution hardening and precipitation hardening, result from the formation of very-fine Cu precipitates. Tensile test results indicated that the yield strength increased and then slightly decreased, while the tensile strength gradually decreased with increasing tempering temperature. On the other hand, the energy absorbed at room and lower temperatures remarkably increased after tempering at 350˚C; and after this, the energy absorbed then did not change much. Suitable tempering treatment remarkably improved both the strength and the impact toughness. In the 1.5 Cu steel specimen tempered at 550˚C, the yield strength reached 1.2 GPa and the absorbed energy at -20˚C showed a level above 200 J, which was the best combination of high strength and good toughness.

Microstructural and mechanical characteristics of Al-6Si-2Cu alloy for lightweight automotive parts were investigated. The test specimens were prepared by gravity casting process. Solution heat treatments were applied to as-cast alloys to improve mechanical properties. The microstructure of the gravity casting specimen presents a typical dendrite structure, having a secondary dendrite arm spacing (SDAS) of 37μm. In addition to the Al matrix, a large amount of coarsened eutectic Si, Al2Cu intermetallic phase, and Fe-rich phases were identified. After solution heat treatment, single-step solution heat treatments were found to considerably improve the spheroidization of the eutectic Si phase. Two-step solution treatments gave rise to a much improved spheroidization. The mechanical properties of the two-step solution heat treated alloy have been shown to lead to higher values of properties such as tensile strength and microhardness. Consequentially, the microstructural and mechanical characteristics of Al alloy have been successfully characterized and are available for use with other basic data for the development of lightweight automotive parts.

A powder-in-sheath rolling (PSR) process utilizing a copper alloy tube was applied to a fabrication of a multi-walled carbon nanotube (CNT) reinforced aluminum matrix composite. A copper tube with an outer diameter of 30 mm and a wall thickness of 2 mm was used as a sheath material. A mixture of pure aluminum powders and CNTs with the volume contents of 1, 3, 5 vol% was filled in the tube by tap filling and then processed to 93.3% height reduction by a rolling mill. The relative density of the CNT/Al composite fabricated by the PSR decreased slightly with increasing of CNTs content, but showed high value more than 98%. The average hardness of the 5%CNT/Al composite increased more than 3 times, compared to that of unreinforced pure Al powder compaction. The hardness of the CNT/Al composites was some higher than that of the composites fabricated by PSR using SUS304 tube. Therefore, it is concluded that the type of tube affects largely on the mechanical properties of the CNT/Al composites in the PSR process.

Rice (Oryza sativa L.) is one of the most important staple foods in Korea and the consumption of brown rice is increasing annually. The objective of this study is to investigate the physicochemical, hydration and textural properties related to eating quality of cooked brown rice by using glutinous, semi-glutinous, four non-glutinous and four colored varieties. The moisture, protein and total dietary fiber contents of brown rice are shown in the range of 11.1~12.6%, 6.6~8.7% and 6.28~12.40%, respectively. The amount of water uptakes for brown rice during the hydration has shown significant differences. The glutinous variety of Boseogchal indicate the highest water absorption levels by reaching 0.38 gH2O/g. The hardness of hydration for Seolgaeng is distinctively lower than those of the other brown rice varieties. According to the textural characteristics of cooked brown rice when using the Tensipresser, the hardness of Boseogchal, Baegjinju and Seolgaeng all exhibit the lowest values out of ten varieties and the highest levels of adhesiveness.

본 연구는 규모가 작고 역동적인 벤처기업의 성장에 영향을 줄 수 있는 요인들 중에서 기업의 전략적 행동이나 경영자의 경영 역량과 관련된 제품 전략과 CEO(최고경영자) 특성의 효과를 실증적으로 분석하였다. 벤처기업의 표본을 이용하여 FGLS 추정법에 기반한 회귀분석의 결과에 따르면, 제품 전략과 CEO 특성은 기업 성장에 유의한 영향을 주며 추가적인 설명력을 가진다. 일반적으로 제품의 다양화와 마케팅을 강조할수록, 변화혁신을 완화할수록 성장률이 높았다. 그리고 CEO가 경영지배력을 가진 창업자가 아니거나, 현재 사업관련 분야에서 실무경험이 많을수록 성장률이 높았다. 또한, 연구개발 위주 업무경력보다 일반경영 중심의 업무경력을 가진 CEO가 관리하는 기업이 성장률이 더 높았다. 제품 전략과 CEO 특성이 벤처기업의 성장에 미치는 이런 효과들은 조직수명주기 단계에 따라서 달라졌다. 창업기 및 초기 성장기에 있는 기업에서 제품의 마케팅 강조 전략과 CEO의 일반경영 중심 업무경력이 기업 성장에 미치는 긍정적 효과가 상대적으로 강화된 반면, 성숙기 및 정체기에 있는 기업에서 이런 제품 전략과 CEO 특성이 기업 성장에 미치는 효과가 부정적이거나 유의하지 않았다.

본 연구는 다양한 수준의 셀레늄 강화 청보리 사일리지 와 무기셀레늄을 급여 시 비육기 거세한우의 생산성, 혈액 성상, 도체특성 및 조직 내 셀레늄 축적에 미치는 영향을 조사하였다. 시험은 거세비육우 20두를 공시하였고, 처리구 는 셀레늄 수준에 따라 0.1 ppm Se(대조구), 0.3 ppm Se (T1), 0.9 ppm Se (T2) 및 무기셀레늄 0.9 ppm Se (T3) 급 여구로 4처리를 나누어 처리구 구당 5두씩 완전임의 배치 하여 90일간 사양시험을 실시하였다. 각 시험사료는 셀레 늄 강화 및 셀레늄 무처리 관행 청보리 사일리지를 조합하 여 건물기준 30% 함유하도록 배합하였다. 실험사료 내에 셀레늄 강화수준은 사료섭취량과 증체에 영향을 미치지 않 았고, 혈중 총 지질과 중성지방농도는 대조구보다 T2구가 유의하게 낮았다(p<0.05). 혈중 면역글로불린은 셀레늄함유 량이 많을수록 높게 나타나 T2와 T3구가 대조구보다 유의 하게 높았다(p<0.05). 혈중 셀레늄농도는 유기태 셀레늄을 0.9 ppm 급여한 T2구가 가장 높았다(p<0.05). 도체율, 배최 장근, 등지방두께, 근내지방도, 육색 및 지방색은 셀레늄급 여로 인한 효과가 나타나지 않았다. 또한, 사료 내 셀레늄 수준 및 형태는 육질 및 육량등급 간에 관련성이 형성되지 않았다. 신장, 간장 및 후지 내 셀레늄 함량은 사료 내 셀 레늄 강화수준이 증가함에 따라 유의하게 직선적으로 증가 하였고(p<0.05), 무기셀레늄급여는 대조구와 유의한 차이가 나타나지 않아, 조직 내 셀레늄함량 증가에 도움이 되지 않았다(p>0.05). 이상의 결과에서 셀레늄 강화 청보리 사일 리지 내 존재하는 셀레늄은 조직 내 셀레늄함량을 증가시 키기에 유효한 셀레늄급원인 것으로 나타났고, 셀레늄 강 화 청보리 최고수준(0.9 ppm Se)으로 급여하여 생산된 한 우 후지육 100 g에 함유되어 있는 셀레늄은 성인기준 1일 최소 셀레늄 권장량(40 ㎍)의 약 69%를 충족시키는 것으로 조사되었다.

본 연구에서는 내식성이 우수한 동합금에 대하여 내구성 향상을 위해 쇼트피닝 시간을 변수로 표면 개질하여 전기화학적 특성과 조직 변화를 관찰하였다. 그 결과 쇼트피닝 후 표면에 전체적으로 요철이 발생하였으며, 시간이 증가할수록 커버리지 향상에 따른 균질화 현상이 관찰되었다. 또한 쇼트피닝된 모든 시험편에서 경도가 향상되었으며, 쇼트피닝 시간이 3.5분일 때 52 %의 경도향상을 나타냈다. 그리고 이때 전기화학적 특성은 쇼트피닝을 실시하지 않은 경우와 유사하였다

This study investigated the continuous cooling transformation, microstructure, and mechanical properties of highstrength low-alloy steels containing B and Cu. Continuous cooling transformation diagrams under non-deformed and deformed conditions were constructed by means of dilatometry, metallographic methods, and hardness data. Based on the continuous cooling transformation behaviors, six kinds of steel specimens with different B and Cu contents were fabricated by a thermomechanical control process comprising controlled rolling and accelerated cooling. Then, tensile and Charpy impact tests were conducted to examine the correlation of the microstructure with mechanical properties. Deformation in the austenite region promoted the formation of quasi-polygonal ferrite and granular bainite with a significant increase in transformation start temperatures. The mechanical test results indicate that the B-added steel specimens had higher strength and lower upper-shelf energy than the B-free steel specimens without deterioration in low-temperature toughness because their microstructures were mostly composed of lower bainite and lath martensite with a small amount of degenerate upper bainite. On the other hand, the increase of Cu content from 0.5 wt.% to 1.5 wt.% noticeably increased yield and tensile strengths by 100 MPa without loss of ductility, which may be attributed to the enhanced solid solution hardening and precipitation hardening resulting from veryfine Cu precipitates formed during accelerated cooling.

Mo-based thin films are frequently used as back electrode materials because of their low resistivity and high crystallinity in CIGS chalcopyrite solar cells. Mo:Na/Mo bilayer thin films with 1μm thickness were deposited on soda lime glass by varying the thickness of each layer using dc-magnetron sputtering. The effects of the Mo:Na layer on morphology and electrical property in terms of resistivity were systematically investigated. The resistivity increased from 159μΩcm to 944μΩcm; this seemed to be caused by increased surface defects and low crystallinity as the thickness of Mo:Na layer increased from 100 nm to 500 nm. The surface morphologies of the Mo thin films changed from a somewhat coarse fibrous structures to irregular and fine celled structures with increased surface cracks along the cell boundaries as the thickness of Mo:Na layer increased. Na contents varied drastically from 0.03 % to 0.52 % according to the variation of Mo:Na layer thickness. The change in Na content may be ascribed to changes in surface morphology and crystallinity of the thin films.

Recently, steel structures have increasingly been required to have sufficient deformability because they are subjected to progressive or abrupt displacement arising from structure loading itself, earthquake, and ground movement in their service environment. In this study, high-strength low-carbon bainitic steel specimens with enhanced deformability were fabricated by varying thermo-mechanical control process conditions consisting of controlled rolling and accelerated cooling, and then tensile and Charpy V-notch impact tests were conducted to investigate the correlation between microstructure and mechanical properties such as strength, deformability, and low-temperature toughness. Low-temperature transformation phases, i.e. granular bainite (GB), degenerate upper bainite(DUB), lower bainite(LB) and lath martensite(LM), together with fine polygonal ferrite(PF) were well developed, and the microstructural evolution was more critically affected by start and finish cooling temperatures than by finish rolling temperature. The steel specimens start-cooled at higher temperature had the best combination of strength and deformability because of the appropriate mixture of fine PF and low-temperature transformation phases such as GB, DUB, and LB/LM. On the other hand, the steel specimens start-cooled at lower temperature and finish-cooled at higher temperature exhibited a good low-temperature toughness because the interphase boundaries between the low-temperature transformation phases and/or PF act as beneficial barriers to cleavage crack propagation.

A two-pass differential speed rolling(DSR) was applied to a deoxidized low-phosphorous copper alloy sheet in order to form a homogeneous microstructure. Copper alloy with a thickness of 3 mm was rolled to 75 % reduction by two-pass rolling at 150˚C without lubrication at a differential speed ratio of 2.0:1. In order to introduce uniform shear strain into the copper alloy sheet, the second rolling was performed after turning the sample by 180˚ on the transverse direction axis. Conventional rolling(CR), in which the rotating speeds of the upper roll and lower roll are identical to each other, was also performed by two-pass rolling under a total rolling reduction of 75 %, for comparison. The shear strain introduced by the conventional rolling showed positive values at positions of the upper roll side and negative values at positions of the lower roll side. However, samples processed by the DSR showed zero or positive values at all positions. 100//ND texture was primarily developed near the surface and center of thickness for the CR, while 110//ND texture was primarily developed for the DSR. The difference in misorientation distribution of grain boundary between the upper roll side surface and center regions was very small in the CR, while it was large in the DSR. The grain size was smallest in the upper roll side region for both the CR and the DSR. The hardness showed homogeneous distribution in the thickness direction in both CR and DSR. The average hardness was larger in CR than in DSR.